Methods for spatial-based power savings

ABSTRACT

Described herein are systems and methods that reduce power consumption for an electronics device that includes a display. Power conservation systems and methods described herein alter video information in one or more inactive portions of a display area such that the alteration decreases power consumption. The invention finds use with many electronics devices, such as portable computing devices powered from a battery or other limited source of power. Since video output often dominates power consumption for an electronics device, decreasing display power consumption may extends battery longevity for the portable device.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application and claims priority under35 U.S.C. §120 from commonly-owned and co-pending U.S. patentapplication Ser. No. 10/891,734, filed Jul. 15, 2004 and titled“SPATIAL-BASED POWER SAVINGS”, which claimed priority under 35 U.S.C.§119(e) from U.S. Provisional Patent Application No. 60/487,761 filed onJul. 16, 2003; each of these applications is incorporated herein byreference for all purposes.

BACKGROUND OF THE INVENTION

This invention relates to systems and methods for reducing powerconsumed by an electronics device that includes a display. Moreparticularly, the present invention relates to spatial-based techniquesfor conserving power based on inactive portions of a display area.

Video output for a desktop or laptop computer typically consumes between70 and 95 percent of the computer's power budget. Other electronicsdevices such as handheld portable computing devices and MP3 playersinclude similarly large video consumption rates.

Currently, power conservation techniques alter an entire image at once,such as shutting down a computer after some predetermined time orapplying some other ‘sleep’ or ‘hibernate’ mode that turns off all videooutput for an entire display area.

Many consumers equate antiquated screen savers directed to preventingscreen burn-in with a power conservation tool. Screen burn-in, aphenomenon associated with cathode ray tube (CRT) devices, occurs whenphosphors on an internal surface of a CRT screen deteriorate over timedue to the frequent presence of currents required for creating visualoutput. Parts of a CRT screen that continually receive fewer videoimages will not experience as much burn-in as parts that receive morefrequent output. Eventually, a noticeable difference grows in a CRTscreen between regions of high activity and regions of low activity.Screen savers were thus historically developed for CRT display devicesto prevent screen burn-in from accumulating.

In computer operation, a graphics control initiates the screen saverafter some predetermined time and replaces computer video content acrossthe entire screen with new and different screen saver video content.Screen savers only reduce power consumption when the energy required forthe screen saver video is less than the energy required for the computercontent previously displayed. Many screen savers, such as picture slideshows, may consume more energy than the previous video content. Inaddition, graphics-based user interfaces run a screen saver across anentire screen. These rules intend to protect CRT life, regardless ofpower consumption.

Based on the foregoing, it should be apparent that improved powerconservation techniques would be desirable.

SUMMARY OF THE INVENTION

The present invention provides systems and methods that reduce powerconsumption for an electronics device that includes a display. The powerconservation systems and methods alter video information in one or moreportions of a display area such that the alteration decreases powerconsumption.

In one aspect, the present invention relates to a method for reducingpower consumed by a display device. The method comprises displaying anactive graphics component in a first portion of a display area providedby the display device. The method also comprises altering videoinformation in an inactive portion of the display area that is outsidethe first portion in response to user inactivity in the inactiveportion. The video information is altered such that the display devicewill consume less power when displaying the altered video informationthan an amount of power that would be required to display the videoinformation without the alteration. The method further comprisessimultaneously displaying the active graphics component in the firstportion and the altered video information in the inactive portion.

In a luminance reduction aspect, the present invention relates to amethod for reducing power consumed by a display device. The methodcomprises displaying an active graphics component in a first portion ofa display area provided by the display device. The method also comprisesreducing luminance for a set of pixels in an inactive portion of thedisplay area that is outside the first portion in response to userinactivity in the inactive portion. The luminance is reduced such thatthe display device will consume less power when displaying the reducedluminance video information than an amount of power that would berequired to display the video information without the luminancereduction. The method further comprises simultaneously displaying theactive graphics component in the first portion and the reduced luminancevideo information in the inactive portion.

In another aspect, the present invention relates to a computer readablemedium including instructions for reducing power consumed by a displaydevice. The computer-readable medium comprises instructions fordisplaying an active graphics component in a first portion of a displayarea provided by the display device. The computer-readable medium alsocomprises instructions for altering, in response to user inactivity inan inactive portion of the display area that is outside the firstportion, video information in the inactive portion. The videoinformation is altered such that the display device will consume lesspower when displaying the altered video information than an amount ofpower that would be required to display the video information withoutthe alteration. The computer-readable medium further comprisesinstructions for simultaneously displaying the active graphics componentin the first portion and the altered video information in the inactiveportion.

In yet another aspect, the present invention relates to a system forreducing power consumed by a display device. The system comprises amonitoring apparatus designed or configured to monitor user activity ina display area for the display device and separate the display area intoan active portion based on user activity in the active portion and aninactive portion that is outside the active portion. The system alsocomprises a power conservation apparatus designed or configured toreceive user activity information produced by the monitoring apparatus,to alter video information in the inactive portion such that the displaydevice will consume less power when displaying the altered videoinformation than an amount of power that would be required to displaythe video information without the alteration, and to output the alteredvideo information.

In still another aspect, the present invention relates to a system forreducing power consumed by a display device. The system comprises amonitoring apparatus designed or configured to monitor user activity ina display area for the display device and separate the display area intoan active portion based on user activity in the active portion and aninactive portion that is outside the active portion. The system alsocomprises a power conservation apparatus designed or configured toreceive user activity information produced by the monitoring apparatus,to alter video information in the inactive portion such that the displaydevice will consume less power when displaying the altered videoinformation than an amount of power that would be required to displaythe video information without the alteration, and to output the alteredvideo information. The system further comprises at least one displaybuffer designed or configured to receive the altered video informationand output, to the display device, a) active portion video informationfor display in the active portion of the display area, and b) thealtered video information for display in the inactive portion, which isfor display while the active portion video information is displayed.

In yet another power conservation aspect, the present invention relatesto a system for reducing power consumed by a display device. The systemcomprises a monitoring apparatus designed or configured to monitor useractivity in a display area for the display device and to separate thedisplay area into an active portion based on user activity in the activeportion and an inactive portion that is outside the active portion. Thesystem also comprises a power conservation control designed orconfigured to receive user activity information provided by themonitoring apparatus, determine a alteration for the video informationin the inactive portion such that the display device will consume lesspower when displaying the altered video information than an amount ofpower that would be required to display the video information withoutthe alteration, and output a signal indicative of the alteration. Thesystem further comprises a video adaptor designed or configured toreceive the signal from the power conservation control, to alter thevideo information in the inactive portion based on the signal, and tooutput the altered video information. The system additionally comprisesat least one display buffer configured to receive the altered videoinformation and output, to the display device, a) active portion videoinformation for display in the active portion of the display area, andb) the altered video information for display in the inactive portion,which is for display while the active portion video information isdisplayed.

These and other features of the present invention will be presented inmore detail in the following detailed description of the invention andthe associated figures.

Before committing to the Detailed Description, it may facilitateunderstanding to clarify certain words and phrases used in this patentdocument: the terms “include” and “comprise,” as well as derivativesthereof, mean inclusion without limitation; the term “or,” is inclusive,meaning and/or; the phrases “associated with” and “associatedtherewith,” as well as derivatives thereof, may mean to include, beincluded within, interconnect with, contain, be contained within,connect to or with, couple to or with, be communicable with, cooperatewith, interleave, juxtapose, be proximate to, be bound to or with, have,have a property of, or the like. Support and definitions for certainwords and phrases are provided throughout this patent document, andthose of ordinary skill in the art should understand that in many, ifnot most instances, such support applies to prior, as well as futureuses of such words and phrases.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates two graphics components and a background inaccordance with one embodiment of the present invention.

FIG. 1B illustrates alteration to a background and a second graphicscomponent of FIG. 1A as a result of inactivity outside an activegraphics component in accordance with one embodiment of the presentinvention.

FIG. 1C illustrates alteration to the other graphics component of FIG.1A as a result of inactivity outside the second graphics component inaccordance with one embodiment of the present invention.

FIG. 1D shows an exemplary histogram and altered video information forbackground of FIG. 1A.

FIG. 1E illustrates a visual information reduction mechanism employed bythe human vision system that allows a person to recognize objects basedon shape.

FIG. 2A illustrates a system for reducing power consumed by a displaydevice in accordance with one embodiment of the present invention.

FIG. 2B illustrates a system for reducing power consumed by a displaydevice in accordance with a specific embodiment of the presentinvention.

FIG. 3 illustrates a power conservation graphics control for applyingpower conservation techniques in accordance with one embodiment of thepresent invention.

FIG. 4A illustrates a process flow for reducing power consumed by adisplay device in accordance with one embodiment of the invention.

FIG. 4B illustrates a process flow for reducing power consumed by adisplay device in accordance with one embodiment of the invention.

FIG. 4C illustrates a process flow for reducing luminance in one or moreinactive portions in accordance with one embodiment of the invention.

FIG. 5 illustrates an exemplary computer system suitable forimplementing the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described in detail with reference toa few preferred embodiments thereof as illustrated in the accompanyingdrawings. In the following description, numerous specific details areset forth in order to provide a thorough understanding of the presentinvention. It will be apparent, however, to one skilled in the art, thatthe present invention may be practiced without some or all of thesespecific details. In other instances, well known process steps and/orstructures have not been described in detail in order to notunnecessarily obscure the present invention.

In one aspect, the present invention reduces power consumption based onusage distribution across a display area. In this case, the display areais divided into active and inactive portions. For example, a displayarea presented by a display device may be divided into three or fourgraphics components, each related to an individual program running onthe computer. While one graphics component program—such as a wordprocessing file—is active and used, video information for the otherinactive graphics components and inactive portions of the display areais altered to decrease power consumption for the inactive portions.

Altering video information to reduce power consumption may comprisedecreasing the brightness and luminance for inactive video information,altering color for inactive video information, and turning inactivevideo information to black, for example. Power conservation systemdesigners and/or users may also vary the rate of inactive videoinformation change and/or set a lower limit for alterations and videoinformation presentation.

In another embodiment, the present invention alters different inactiveportions at different rates and to varying extents. For example, videoinformation in a background may be altered at a slower rate and lessaggressively than alterations to one or more graphics components (orvice versa).

Video information within a single inactive graphics component may alsobe altered separately. For example, a window that outputs videoinformation for a drawing program may include a border portion and amain work area, which usually displays a white backing that will consumemaximal power when displayed. The border portion allows a user toidentify the window based on shape detection (and a color if the borderhas a characteristic color), and may include a text line that designatesthe program name or file currently open. In one embodiment, the presentinvention decreases luminance for video information in the main workarea greater than video information in the border portion. Thismaintains the ability to identify an inactive graphics component andassociated program based on shape and name, while reducing the majorityof power required to display the inactive graphics component.

The present invention finds use with portable computing devices poweredfrom a battery or other limited source of power. Since video outputoften dominates the portable device's power consumption, decreasingvideo power consumption extends battery longevity for the device.

The present invention also finds use with display devices having a largedisplay area size relative to an active graphics component size. Forexample, laptop computers with 15-17″ display areas, measureddiagonally, are now common. Some programs, such as music playerprograms, occupy less than 20% of the display area. Conventional videooutput protocol displays the entire display area—at full power—whenusing the smaller graphics component—even though only a small portion ofthe display area is in use. The present invention however may decreasepower consumption from inactive portions of the display area and therebysave power. In some cases, spatial-based power conservation techniquesdescribed herein may reduce power consumption for an electronics deviceby up to 50%, and even more in some applications.

FIG. 1A illustrates two graphics components 5 and 7 and a background 10in accordance with one embodiment of the present invention. While thepresent invention will now be described as graphics systems andcomponents useful for reducing power consumption, those skilled in theart will recognize that the subsequent description with respect to FIGS.1A-1E may also illustrate methods and discrete actions for reducingpower consumption for a display device and electronics device.

An electronics device, such as a desktop, laptop or handheld computer,runs graphics-based user interface 4 and operates a display device forvisual output. Graphics-based user interface 4 facilitates interactionbetween a user and computing device and/or between the user and one ormore computer programs run on the computer. Graphics components 5 and 7and background 10 are intended for use with interface 4. Graphics-baseduser interface 4 employs the display device to output video informationfor graphics components 5 and 7 and background 10. Graphics-based userinterface 4 also allows user input within background 10 and within eachgraphics component 5 and 7.

Graphics components 5 and 7 are each for display as discrete visualobjects and output video information related to a program running on thecomputer. Common programs include word processing programs, filenavigation displays, Internet Browsers, drawing programs, music playerprograms, and video games, for example. Rectangular windows are commonand vary in size from a maximum size that roughly spans a display area12 to smaller sizes within display area 12. Graphics components 5 and 7may each include their own bitmap comprising an array of pixel values.For FIG. 1A, graphics component 5 is a window that comprises wordprocessing video output 6. Graphics component 7 is a window thatcomprises music player program video output 8.

Background 10 represents a backdrop graphics component forgraphics-based user interface 4. In one embodiment, a perimeter ofbackground 10 determines an allowable usable area for graphics-baseduser interface 4. The usable area defines visual output limits, definesuser input limits for interface 4, and defines other related backgroundfunctions. For example, dimensions for background 10 establish spatiallocations for background graphics components such as icons 11 andcontrol bar 13.

Display area 12 refers to the total image size of a display device.Pixel dimensions may characterize the size of display area 12. Maximallinear dimensions that span an image produced by the display device mayalso characterize the size of display area 12. For a liquid crystaldisplay (LCD), an organic light emitting diode (OLED) device or aprojector, display area 12 may be characterized using the maximum pixeldimensions for an optical modulator producing the image. Thus,resolution for a projector's optical modulation device (e.g., DMD)quantifies the display area 12 size. Linear dimensions for display area12 output by a projector will vary with the distance between thereceiving surface and projector output lens and a splay angle for theprojector. The linear dimensions may be measured on the projected image,usually after any keystone distortion has been suitably corrected for.

FIG. 1B illustrates an altered background 10 and graphics component 7 asa result of inactivity outside an active graphics component 5 inaccordance with one embodiment of the present invention. User activityin this case with graphics-based user interface 4 comprises continuedinteraction within the boundary 5 a of graphics component 5, such astyping and/or pointer positioning within the window boundary 5 a.

The present invention alters video information outside an activegraphics component such that a display device outputting the videoinformation requires less power than an amount of power required withoutalteration. An active graphics component implies activity (orinteraction) between the graphics component and a user. Activity maycomprise a) user input within a perimeter or outer boundary for thegraphics component—as determined by a program associated with thegraphics component, and/or b) program output to the user—as determinedby the program. The perimeter of an active graphics component alsodefines an active portion inside the perimeter and inactive portionoutside the perimeter for video alteration as described herein. Inactiveportions may also be differentiated for video alteration within a singlegraphics component, as will be described below.

Activity that qualifies as active are related to a program associatedwith the graphics component, and may vary with power conservation systemdesign. For example, user input and activity for a word processingprogram running on graphics component 5 may include: typing withinwindow boundary 5 a, positioning a pointer within window boundary 5 a,clicking a button (e.g., using a mouse) within window boundary 5 a,manipulating menus and scrollbars within window boundary 5 a, a subsetof these chosen by design, etc. User input for a music player programrunning on graphics component 7 may include selecting songs to be playedor manipulating volume and other audio output features. Video output forthe music player program may include temporally-varying video thatchanges with the music based on program operation—without regular userinput—such as an equalizer output or a clock that counts music time as asong plays. In one embodiment of the present invention, the music playerprogram maintains an active graphics components status as a result ofthe temporally-varying video output. In another embodiment, the powerconservation system is designed such that temporally-varying videooutput for the music player program does not qualify as activity andgraphics component 7 becomes inactive without any user input oractivity. User input for an Internet browser window may includepositioning a pointer within the window, typing addresses, and openinglinks, for example. In one embodiment, activity comprisestemporally-varying video output provided by a program whose video outputintentionally varies over time without continued user input, such as amovie player. Video output is also common with Internet browsers and mayor may not constitute interaction based on power conservation systemdesign. User input for background 10 includes moving a pointer withinbackground 10, selecting (‘clicking’ or ‘double clicking’) an icon 11,accessing individual items on control bar 13, etc.

Inactivity outside the active graphics component implies a lack ofinteraction in the inactive portion. As activity described above dependson a program associated with the graphics component, so does inactivity.In one embodiment, inactivity is defined for an individual graphicscomponent according to a lack of activity for the graphics component,which will depend on the program associated with the graphics component.Thus, inactivity for word processing graphics component 5 includes alack of typing within the window boundary, a lack of positioning apointer within the window boundary, a lack of manipulating menus andscrollbars within the window boundary, etc. Inactivity for background 10may include a lack of positioning a pointer within the background 10perimeter, a lack of initiating icons and menus, etc. In one embodiment,the present invention discriminates inactivity between background 10 andindividual graphics components outside the active graphics component.

Graphics-based user interface 4 of FIG. 1B uses a threshold inactivitytime to determine when alterations to video information outside ofactive graphics component 5 begin. The threshold inactivity time alsodetermines when power conservation begins. Graphics-based user interface4 may alternately alter video information immediately with inactivity,as described below with respect to FIG. 1C. A user may set the thresholdinactivity time via a graphics control such as that described in FIG. 4.Once the threshold inactivity time has been reached, output power forthe display device decreases according to one or more video manipulationtechniques.

In one embodiment, after the threshold inactivity time, videoalterations and power conservation may continue at set power reductionintervals. The power reduction intervals determine specific times afterthe threshold inactivity time at which further video alterations areapplied. This allows the video information to gradually change—and powerconservation to gradually increase—over time and according to varyingdesign or user preference. A user may set the power reduction intervalsusing a graphics control, such as that described below. In order for apower reduction interval to be met, inactivity continues within theinactive graphics component or inactive portion for the duration of theinterval. It is understood that the threshold inactivity time and powerreduction intervals are a matter of system design and user choice andmay be different time periods.

Once the threshold inactivity time has past, the present inventionalters video information outside an active graphics component such thata display device will consume less power than that which would berequired without alteration. In addition, video information outside theactive graphics component may continue to adapt as time proceeds tofurther reduce power consumption. An array of video manipulationtechniques may be employed by the present invention to reduce powerconsumption. Some techniques manipulate the luminance levels of pixelsin an inactive portion to reduce power consumption.

Human vision employs a number of information reduction mechanisms toreduce the amount of visual information in an environment to amanageable level. Such mechanisms include shape detection andforeground/background separation. Foreground/background separationdivides an environment to into a foreground where more information isprocessed (e.g. more detail) and a background where less information isprocessed (e.g. less detail). Shape detection allows a person torecognize objects based on reduced information, such as outer contoursthat resemble a shape for the object. In one embodiment, the presentinvention leverages these information reduction mechanisms to reduce theamount of video information displayed outside an active graphicscomponent and to reduce power consumption for the display device.

In a specific embodiment, the present invention reduces the amount ofvisual information in an inactive portion. This technique leverages theforeground/background visual processing mechanism in humans. Since anindividual processes less information in a background visual region,reducing video output in an inactive portion may not sacrifice perceivedvideo quality for an active task or graphics component. In someembodiments, the inactive video information is altered while minimizingany compromises for a person to subsequently locate and identify aninactive graphics components, e.g., using shape detection or color.

Power conservation as shown in FIG. 1B reduces luminance for videoinformation in an inactive portion outside of graphics component 5. Inone embodiment, the present invention reduces the luminance for allpixels in the inactive portion by the same amount. In other words, theentire inactive portion becomes darker by subtracting a constant valuefrom the luminance value for each pixel in the inactive portion. Thiseffectively shifts a luminance histogram for the inactive videoinformation to a darker state. Such a luminance reduction may beimplemented at a threshold inactivity time and at each power reductioninterval. The constant value may include a function of i) a maximumluminance for the inactive portion (such as a percentage), ii) a maximumluminance provided by the display device, iii) a mean, median or mode ofluminance values for an inactive portion (e.g., background 10 orgraphics component 7), or iv) a mean, median or mode of a luminancerange values provided by the display device, etc. A suitable percentageof the maximum luminance for the inactive portion may range from about 2percent to about 100 percent of the maximum luminance. A suitablepercentage of the maximum luminance for the display device may rangefrom about 2 percent to about 100 percent of the maximum luminanceprovided by the display device. Thus, a 100 percent reduction turns theentire inactive portion black at the threshold inactivity time andmaximizes energy conservation. A 5 percent luminance reduction at thethreshold inactivity time and each power reduction interval thereaftersteadily decreases luminance over time. Values less than 1 percent maybe used for subtle and/or high frequency changes. While saving lesspower than a full 100 percent reduction, smaller alterations may bepreferable to some users who prefer a less dramatic visual change in theinactive portions. It is also understood that the percentage reductionat the threshold activity time and each power reduction interval may bedifferent levels. For example, a 5 percent luminance reduction may beimplemented at the threshold inactivity time, while a 2 percent, 10percent, or escalating (0.25, 0.5, 1, 2, 4, 6, 8, 10 percent, etc.)reduction may be used at each power reduction interval.

Graphics component 7 of FIG. 1B is illustrated after about 9½ minutes ofinactivity within graphics component 7. In a specific embodiment,graphics component 7 includes a threshold inactivity time of 5 minutesand power reduction intervals of 1 minute. The luminance decrease isabout 10 percent of the maximum luminance provided by the display devicefor both the threshold inactivity time and at each subsequent luminancereduction interval. Thus, after about 9½ minutes of inactivity withingraphics component 7, the luminance reduction is about 40 percent. After14 minutes, the luminance for all pixels and video information withingraphics component 7 will be zero and the visual output for graphicscomponent 7 will be black.

In one aspect, the present invention builds a histogram for a set ofpixels and reduces power consumption for the pixels using one or morehistogram-manipulation techniques. The histogram describes the frequencyof pixel values (e.g., luminance or chroma) for a graphics component orbackground. One embodiment alters pixel values in an inactive portion bycompressing and shifting a luminance histogram. More specifically, aluminance histogram is first constructed for a set of pixels in theinactive portion, such as background 10. The luminance histogram is thencompressed, e.g., about the mean, median or mode. A shift subsequentlyreduces the luminance values for all pixels in the compressed set by aconstant. One suitable constant is a number that gives a pixel with thelowest luminance value in the new compressed histogram a zero luminance.The inactive portion becomes darker since the final histogram luminancevaries from zero luminance to a new maximum luminance produced as aresult of the compression and shift.

FIG. 1D shows an exemplary histogram 20 for background 10 of FIG. 1B. Asshown, histogram 20 is compressed by 20 percent: 10 percent on the lowend 10 percent on the high end. After the compression, all pixelluminance values in the compressed histogram 21 are decreased by aluminance difference 25 between a lowest luminance value for compressedhistogram 21 and zero. A shifted and compressed histogram 27 resultsfrom the two operations and includes luminance values that vary fromzero luminance to a new maximum luminance 22.

This combined compression and shift eliminates high luminance values foran inactive portion. Eliminating the high luminance pixels in aninactive portion decreases power for each individual pixel andcumulatively reduces power consumption for the inactive portion andentire display area. In addition, this combined compression and shiftsomewhat maintains relative luminance levels in the video informationthat existed before the alteration without turning specific portions toblack.

A suitable amount of luminance compression may range from about 1percent to about 50 percent of histogram luminance range for theinactive portion. Another suitable compression may range from about 5percent to about 20 percent of histogram luminance range. Compressionand shifting may occur at the threshold inactivity time and at eachpower reduction interval, if desired. This process may repeat atsubsequent power reduction intervals until the entire inactive portionis almost black or until a predetermined cutoff is reached. Suitablecutoffs include: when the maximum luminance value in the inactiveportion reaches a predetermined minimum luminance, when the histogramreaches a minimum width, or when the difference between subsequentiterations is minimal.

The present invention may implement other compression and shift schemes.In one embodiment, the luminance histogram for a set of pixels iscompressed only on one side, e.g., on the high end. If the histogramcompression occurs just on the high end of luminance values, theinactive portion becomes darker for brighter pixels only. If thehistogram compression occurs only on the low end of luminance values andthen a shift is applied, the inactive portion becomes darker for allpixels.

Although the present invention has primarily been discussed so far withlinear and simple reductions in luminance for pixel values in aninactive portion, a power conservation system designer may apply morecomplicated luminance reduction and power conservation schemes. Therelationship between power reduction, video alterations, and time may beestablished according to system design. One suitable power conservationscheme applies stepwise reductions of predetermined values atpredetermined times. Another power conservation scheme employs anexponential decrease in luminance values for pixels in an inactiveportion as time proceeds. In this case, luminance reduction startsslowly in an initial time span, increases gradually in some midpointtime span, and then increases sharply in a later time span. A linearreduction based on y=F(x²), where y is the current luminance reduction,x represents the ith alteration in a number of alterations over time,and F(x²) is some function that increases power conservation asinactivity time passes or increases exponentially with a number ofalterations to the video information. Linear constants and othermathematical operators may be inserted into the equation to alter videoalterations as desired. Logic may also be applied in the videoinformation manipulation to achieve a desired luminance vs. time curve.

Logic that limits further alterations to pixels in subsequent powerreduction intervals before may also be implemented. One suitable logicapplies a lower limit that values of individual pixels in the inactiveportion may be reduced to, such as a percentage of an initial luminanceor chroma level. For example, luminance reductions may cease for a pixelonce they the pixel reaches from about 5 percent to about 50 percent ofits initial level—regardless of how it reached this point.

In another embodiment, luminance reduction occurs gradually over time atsmaller intermittent time intervals (e.g., less than a minute) and smallluminance alterations, as opposed to larger and less frequentalterations. This technique provides a more gradual power reductionwithout sharp or noticeable changes in video content. For example,luminance in an inactive portion may decrease 1 percent every 10seconds, thereby decreasing luminance by 60 percent over ten minuteswithout a large and obvious single change.

In one embodiment, alterations to video information include differentrates and alterations for different inactive portions. Referring back toFIG. 1B, background 10 and graphics component 7 are altered at differentrates and with different mechanisms. Background 10 includes a backgroundthreshold inactivity time of 2 minutes and power reduction intervals of30 seconds. At each power reduction interval, the histogram forbackground 10 is compressed by 10 percent and shifted down by 5 percent.For the about 9½ minute snapshot illustrated in FIG. 1B, videoinformation in background 10 has been reduced to about 18 percent of itsoriginal luminance span and now occupies the lowest 18 percent of itsluminance values. After 10 minutes, a logical cutoff is implemented tofurther changes and the visual output for background 10 turns black. Thelogical cutoff is implemented to further changes may also keep videoinformation in background 10 at a constant level, such as the level lastaltered to. In one embodiment, alterations to background 10 videoinformation are designed to produce greater power conservation thanalterations to video information for a graphics component. This powerconservation difference incorporates size, video information, andalteration rate variations between a background 10 and any graphicscomponent.

An active portion of display area 12 includes any area in display area12 employed by an active graphics component or active program. Spatiallimits for a graphics component are typically defined by a perimeteraccording to video information in a bitmap for the graphics component.Such spatial description is usually defined by the graphics-based userinterface 4 and known to those of skill in the art. An inactive portionof display area 12 then includes any area in display area 12 outside anactive graphics component or active program. Although FIG. 1B showsgraphics components 5 and 7 as distant structures, it is understood thatgraphics components may overlap. For example, graphics component 5 mayoverlap graphics component 7, or vice versa. In addition, multipleinactive graphics components may overlap. Either active graphicscomponent 5 or 7 also overlaps background 10. Regardless of thegeometric relation of active and inactive graphics components andassociated video information, the present invention applies the powerconservation techniques described herein to any visible inactiveportions and video information. This includes updating changes tobackground 10 when a user drags a graphics component within background10 to expose previously covered portions.

An inactive portion returns—or reactivates—to its original state from analtered state after an explicit user activity in the inactive portion,or after some activity in the program designated as active by a powerconservation program designer. Reactivation displays the videoinformation as it was initially displayed before any alterations. In aspecific embodiment, positioning a pointer onto an area of background 10triggers reactivation and returns background 10 to full luminance.Similarly, graphics component 7 reactivates by positioning a pointerwithin the perimeter of graphics component 7 and/or clicking a buttonwithin the perimeter. Reactivation may also include initiating graphicscomponent 7 via its corresponding toggle 17 on control bar 13, which inthis case may occur without pointer travel through background 10. Powerconservation system designers may also customize reactivation rules. Forexample, reactivation may be designed such that solely positioning andmoving a pointer within a graphics component or background such as awindow does not satisfy reactivation criteria. In this case,reactivation may be satisfied by clicking a button on a mouse while thepointer is within the window, or another explicit action within thegraphics component.

In another embodiment, inactivity within an active window and thedisplay area may be monitored and timed. Graphics-based user interface 4includes a global power saving tool that initiates after a predeterminedtime of inactivity throughout the entire display area 12. In this case,the global power saving tool turns off video display for the entiredisplay area 12 when inactivity within the currently active portionreaches the global power saving tool time limit, e.g., such as 15minutes.

FIG. 1C illustrates an alteration to graphics component 5 and background10 as a result of inactivity outside an active graphics component 7 inaccordance with another embodiment of the present invention. Userinterface in this case with graphics-based user interface 4 comprisescontinued activity within the boundary of graphics component 7.

The present invention advantageously allows a user to access a musicplayer program within graphics component 7—which may constitute arelatively small proportion of display area 12—while reducing videooutput and power consumption from the rest of display area 12. Incontrast, conventional protocol and display devices that singularlydisplay a music player program without the present invention wouldrequire the entire display area to be active and consume power. Forlarger display areas, displaying only graphics component 7 and not theremainder of display area 12 may contribute to up to a 75% reduction inpower consumption, which is particularly valuable when the displaydevice is powered by a battery in a portable computer.

In a specific embodiment, video information outside graphics component 7alters immediately upon inactivity outside graphics component 7. In thiscase, luminance for an entire inactive portion—including background 10and graphics component 5—decreases gradually as time proceeds. Onesuitable luminance reduction scheme decreases luminance incrementallyand alters the video information at power reduction intervals that beginimmediately upon user inactivity and have a frequency of greater thanabout 1 hertz, such as every 50 milliseconds. In this case, theincremental reductions decrease luminance by a tiny amount each timesuch that any individual alteration is barely noticeable to a user.Cumulatively however, the incremental alterations may accumulate toproduce a significant change, such as a 50 percent reduction inluminance for background 10 and graphics component 7 over five minutesfor example. The gradual rate of luminance reduction may be establishedaccording to power conservation system design or user preference, andadvantageously allows inactive portions to alter without a substantiallynoticeable stepwise changes. A magnitude for each incremental alterationmay be determined by dividing a desired total alteration over a periodof time by the number of intervals in the time period.

The present invention may also discriminate what video information isaltered. In one embodiment, alterations to video information outsideactive graphics component 7 modify video information for a graphicscomponent based on whether the information is useful for shapediscrimination and identification of the graphics component. In thiscase, video information outside graphics component 7 is altered suchthat video information useful for shape detection of inactive graphicscomponent 5 is altered less than video information not significantlyuseful for shape detection of inactive graphics component 5. In somecases, the video information useful for shape detection of inactivegraphics component 5 is not altered at all. As described above, shapedetection is a visual information reduction mechanism employed by thehuman vision system that allows a person to recognize objects andgraphics components based on reduced information—namely, the shape ofthe object or graphics component. FIG. 1E illustrates this mechanism fora simple cross 30. As shown, a person's visual system processes an edgepattern 32, while disregarding information in internal portion 34. Thisreduces the amount of information processed by the person. The presentinvention may leverage this human processing scheme to reduce the amountof power output by display device without sacrificing the ability for auser to identify and locate inactive graphics components outside anactive portion.

Graphics component 5 may be spatially characterized and recognized byits border shape 5 a. As highlighted in FIG. 1C, graphics component 5comprises an internal portion 19 within a border portion 21, whichcharacteristically resembles the shape of the rectangular wordprocessing window. Internal portion 19, which mainly comprises text fora word processing window, includes video information not generallyrequired for shape detection of the window. As shown, internal portion19 is heavily reduced in luminance, while border portion 21 is alteredless. This allows a user to identify the graphics component 5 based onshape detection and to detect the presence and position of graphicscomponent 5 using border portion 21, while heavily reducing video outputand power consumption for the internal portion 19. Since internalportion 19 may constitute over 90 percent of the area for graphicscomponent 5, and often includes a white background that usesconsiderable power, luminance reduction in this case may significantlyincrease power conservation while maintaining user recognition.

In one embodiment, alterations according to the present invention mayconsider chroma values. Detection of an inactive graphics component 5may be enhanced using the preservation of characteristic colorinformation for a program displayed by the graphics component.Correspondingly, power conservation and/or recognition of key featuresmay be enhanced using color. Referring back to FIG. 1C, thegraphics-based user interface may user a characteristic color for borderportion 21 of graphics component 5 such as those used with wordprocessing programs and file navigation displays. If the characteristiccolor is blue for example, then video information in internal portion 19may be reduced in color to reduce power, while the color in borderportion 21 may be altered less and preserved to permit quick color-basedrecognition of graphics component 5 and its spatial limits.

In many graphics-based user interface designs, graphics component 5includes text 23 within a border portion 21 that identifies graphicscomponent 5. For a word processing window for example, text 23 mayinclude a specific file name and the program name. For a music playerprogram, text 23 may include the player program name. For a filenavigation display, text 23 may include the current file or directory.In one embodiment, the present invention alters border portion 21 lessand maintains more detail such that the text remains visible. This shapeand border discrimination technique allows a user to scan an altereddisplay area 12, read text 23, and identify graphics component 5 amongsta number of similar word processing windows without a need forreactivating the entire display area 12.

In one embodiment, video information and inactive portions withinbackground 10 are delineated as separate portions and are altered withdifferent rates and mechanisms than a main portion of background 10. Asshown, control bar 13 and any toggles included therein do not decreasein luminance over time. Since control bar 13 represents a relativelysmall portion of display area 12, and a likely place for subsequent userinteraction outside of the currently active graphics component 5, powerconservation may be sacrificed for an expected demand of control bar 13usage. Icons 11 and clock 16 may also be left unaltered or less alteredaccording to power conservation system design.

In a specific embodiment, the present invention alters video informationfor icons 11 such that border portions for each icon are subsequentlyillustrated with increased video information and salience than internalportions of each icon. This allows icons 11 to be recognized based onthe shape or color without requiring full video output from each icon.

To facilitate shape detection based information alteration and powerconservation as described above, the present invention may also employone or more automated edge detection techniques for graphics componentsthat do not readily include characteristic perimeter information intheir bitmap. The edge detection techniques are used to build aperimeter or shape based on video information included in the graphicscomponent bitmap. The perimeter information may also be used to definespatial limits for active and inactive delineation. In this case, ashape detection tool probes video information in an image file accordingto one or more edge detection, contour tracing and shape measurementtechniques and constructs perimeter information for the graphicscomponent. Some common edge detection techniques include a Robert'sGradient, Sobel masks, Prewitt masks, Kirsh masks, LaPlacian filters,isotropic border extractions, etc. Edge detection techniques are knownto those of skill in the art and not detailed herein for sake ofbrevity. After edge detection is complete, the present invention maythen alter video information for the graphics component based on theresults of the edge detection.

According to common graphics-based user interface protocol, a graphicscomponent that does not fill the entire display area may be moved withindisplay area 12. Many graphics-based user interfaces include ‘click anddrag’ functionality that allows a user to reposition graphics componentsuch as a window by moving an on-screen pointer or manipulanda to anedge of the window, pressing a key, and repositioning the window whilethe button is pressed. In one embodiment, repositioning graphicscomponent 7 does not activate inactive graphics components includingbackground 10 or graphics component 5, and as described above, causespreviously hidden video information to appear at the alteration statecurrently occupied by the background. In another embodiment,repositioning a graphics component activates the background and allother graphics components.

Although the present invention has been described so far with respect toalterations in video information and power conservation according toluminance alterations as might be applied in a hue/saturation/luminance(HSL) color scheme, one of skill in the art will appreciate that thealterations described herein may apply to black and white video outputand color video output; and apply regardless of the color schemeemployed by a color video output graphics-based user interface, videocontroller or display device. An HSL color scheme characterizes videooutput according to a wavelength or color (hue), degree of purity of thecolor—or degree of separation from gray having the same color(saturation), and degree of brightness for the color ranging from blackto white (luminance). Red, green, blue (RGB) color schemes are alsopopular and characterize video output from a display device according tocombinations of red, green and blue values. Cyan, magenta, yellow andblack (CMYK) is another color scheme regularly used to characterizevideo output from display device according to combinations of cyan,magenta, yellow and black values.

Translation between the color schemes is well known to one of skill inthe art. Although the present invention has been described so far withrespect to alterations in luminance in an HSL scheme, one of skill inthe art will appreciate that power conservation techniques describedherein may be programmed or stored according to one color scheme, andoutput according to another color scheme on the display device. Forexample, video data manipulation techniques described herein may beprogrammed or stored in an HSL scheme, and then converted to andimplemented on an RGB based display device. Many output devices employan RGB color scheme for video output. These display devices may includea red, green, and blue optical modulation element for each pixel, suchas individual RGB light emitting diode emitters for an OLED displaydevice, individual RGB filters for an LCD device, or a digitalmicromirror element used in a projector that sequentially andselectively reflects incident red, green and blue light from a lamp andcolor wheel into a projection lens. In an RGB based device, individualoptical modulation elements receive commands for video output thatinclude RGB values between 0 and 255 to produce a desired video outputfor a pixel. For example, one greenish color may initially comprisered/green/blue values of 45/251/62. According to luminance reductiontechniques described above, the color may be darkened to 3/155/16, andsubsequently darkened again to 2/90/9 (this maintains the same hue forthe greenish color).

For an OLED display, the amount of current sent to an individual lightemitting diode or filter increases with each color level between 0 and255. Decreasing the color level for each RGB diode then reduces theamount of power for each pixel. More specifically, darkening andreducing luminance for a blue color having initial RGB values of72/48/253 to 20/2/157 and again to Nov. 1, 1991 reduces the amount ofcurrent sent to each individual light emitting diode for each pixel. Theamount of power conserved can then be determined by the known amount ofcurrent saved for all pixels in the inactive portion that are similarlyaltered.

FIG. 2A illustrates a system 50 for reducing power consumed by a displaydevice in accordance with one embodiment of the present invention. Whilethe present invention will now be described as an apparatus composed ofunits, those skilled in the area will recognize that the presentinvention encompasses a method, process or software having as steps theactions performed by each unit and described below. System 50 comprisesmonitoring apparatus 54 and power conservation apparatus 56. In general,system 50 may comprise any combination of software and hardware forcarrying out actions described herein. In one embodiment, monitoringapparatus 54 and power conservation apparatus 56 are implemented solelyin software stored on a computer and run by a processor (such as a videoor graphics chip or main processor). In another embodiment,general-purpose computer processing units, instead of dedicatedhardware, implement the monitoring, active and inactive portionmanagement, and video alteration techniques.

Coupled to system 50 are input device 52 and display device 58. Inputdevice 52 allows a user to position a pointer within a display area ofdisplay device 58. Digitization of information provided by input device52 will be described in further detail with respect to FIG. 5. Somepopular input devices include a mouse, a position-sensing pad on alaptop computer, a stylus working in cooperation with a position-sensingdisplay on a PDA, a positioning knob included on a keyboard of a laptopcomputer, one or more arrow keyboard keys, one or more buttons on a PDA,etc.

Monitoring apparatus 54 is designed or configured to monitor useractivity in a display area for display device 58 and separate thedisplay area into an active portion based on user activity in the activeportion and an inactive portion that is outside the active portion. Todo so, monitoring apparatus 54 is configured to receive digitalinformation from input device 52 that describes spatial input from auser and is configured to access digital representations of spatialareas for individual graphics components in the display area. Monitoringapparatus 54 then compares digital information from input from device 52and the digital representations, and differentiates between active andinactive portions of the display area. Monitoring apparatus 54 may alsoprovide temporal information with regard to user activity by referencinguser activity against temporal information received from a clock source.On one or more output lines, monitoring apparatus may output useractivity information including: a) active and inactive portions of thedisplay area, b) spatial information based on the position(s) of apointer operated by the user, and c) temporal information related touser activity, such as an amount of time that each active and inactiveportion has maintained its active and inactive status, respectively.

Power conservation apparatus 56 is designed or configured to receiveuser activity information produced by the monitoring apparatus 54. Powerconservation apparatus 56 is designed or configured to alter videoinformation in the inactive portion such that display device 58 willconsume less power when displaying the altered video information than anamount of power that would be required to display the video informationwithout the alteration. Several techniques that reduce power consumptionfor display device 58 based on video information alterations werediscussed with respect to FIGS. 1A-1E. Power conservation apparatus 56outputs the altered video information to display device 58. Whileapparatus 56 has been described as a discrete device, those skilled inthe art will realize that apparatus 56 may include software that outputsa control signal useful for altering video information.

Display device 58 displays video information. In one embodiment, displaydevice 58 outputs video information onto a screen comprising array ofpixels. Display device 58 receives the altered video information frompower conservation apparatus 56 or a buffer included in or associatedwith apparatus 56, and displays a) active portion video information inthe active portion of the display area, and b) the altered videoinformation in the inactive portion while the active portion videoinformation is displayed.

Display device 58 varies its power consumption with video output. In oneembodiment, display device 58 varies power consumption with the spatialdistribution of light output in a display area. One such display deviceemploys organic light emitting diodes (OLED) for video output. OLEDdisplays are current driven devices where the intensity of light outputfrom an OLED display is proportional to electrical current flow. Poweroutput for the OLED device spatially varies by controlling andmodulating electrical current levels through individual elements thatare arranged for each pixel. For a color display, each pixel usuallycomprises three OLED element assemblies: one for red light, a second forblue light, a third for green light. Each assembly produces the colorlight directly or uses a colored filter, and RGB values are producedaccording to current input proportional to an RGB value, say from 0 to255. Reducing RGB values for individual pixels—or RGB values via aluminance reduction—as described herein reduces power consumption foreach assembly and each pixel, thereby cumulatively reducing current andpower requirements for the an OLED display device. OLED displays arebecoming increasingly popular for portable and battery powered devices,making power conservation techniques described herein particularlyuseful to conserve limited quantities of battery power. In anotherembodiment, display device 58 comprises a backlit LCD screen. In aspecific embodiment, power conservation is attained by reducing backlitluminance for the entire screen or portions thereof while increasingtransmittance for active areas at the reduced luminance.

The present invention is intended to be independent of any specificmechanism for light generation, power consumption or power savings for adisplay device, and only assumes that power consumption for displaydevice 58 may vary with the spatial distribution of light output. Thepresent invention may also be employed by cathode ray tube devices thatwould save energy by not supplying video information and power toinactive portions of the display screen. In addition, display devicesthat require power for addressing individual pixels for video output,such as those that require individual activation or addressing based onan RGB color scheme (e.g., filtering for LCD displays used in laptopcomputers), may also benefit from present invention by reducing powerrequired to address or activate each color or filter element.

The present invention is particularly useful with display devices havinga large display area. A user may often elect to use only a portion ofthe large display area. For example, a graphics component may includevideo output for menu or a word processing program that only covers alimited amount of a display area for device 58. In this case, thepresent invention alters video output outside these portions to reducepower required for the entire image.

Handheld computing devices are becoming increasingly popular. Mosthandheld devices are designed to regularly run from battery power. Thepresent invention allows a handheld device to unequally consume poweracross its display area based on output video content. Thus, controlmenus and toggles, a clock, and frequently selected graphics componentsmay include video information that is altered less while a mainbackground portion is altered more aggressively to conserve power. Sincethese control items and frequently selected graphics may occupy lessthan 20% of the display area for these handheld devices, powerconservation in this case may contribute to significant power savingsand extended battery life for the handheld device.

FIG. 2B illustrates a system 60 for reducing power consumed by a displaydevice 58 in accordance with a specific embodiment of the presentinvention. While this embodiment of the present invention will now bedescribed as an apparatus composed of units, those skilled in the areawill recognize that the present invention encompasses a method, processor software having as steps the actions performed by each unit anddescribed below.

System 60 comprises activity monitoring apparatus 64 and powerconservation apparatus 66. Input device 52 and display device 58 weredescribed with respect to FIG. 2A. Power conservation apparatus 66comprises power conservation control 68, clock 62, edge detectionapparatus 79, power control logic 70, at least one video buffer 72,video adaptor 74, power sensor 76, and at least one output video buffer78. Each of the components for system 60 may be implemented in hardware,firmware or software, or a combination thereof. It should be noted thatthe functionality associated with a particular component may becentralized or distributed, whether locally or remotely.

Monitoring apparatus 64 separates a display area into an active graphicscomponent based on user activity in a perimeter of the active graphicscomponent. The perimeter defines the active portion and one or moreinactive graphics components that are outside the active portion. Inthis case, display area includes four graphics components and monitoringapparatus 64 stores, or accesses data storage facilities that store, theposition and parametric spatial boundaries for graphics components GC(a)65 a, GC(b) 65 b, GC(c) 65 c, GC(d) 65 d, and background 65 e. Based onuser activity within the display area, monitoring apparatus designatesany one of GC(a) 65 a, GC(b) 65 b, GC(c) 65 c, GC(d) 65 d, andbackground 65 e as the active graphics component. The designation isbased on user activity in a perimeter of one of the graphics component.The perimeter for this active graphics component then defines the activeportion of the display area. The display area outside this perimeterdefines the inactive portions of the display area. The other graphicscomponents in this inactive area are then designated as inactive. Forexample, if GC(b) 65 b is designated as active, graphics componentsGC(a) 65 a, GC(c) 65 c, GC(d) 65 d, and background 65 e are designatedas inactive. Monitoring apparatus 64 has an input that from input device52, shape detection apparatus 79 and an input that receives temporalcalibration from clock 62 and provides temporal information with regardto user activity. Monitoring apparatus 64 has an output that providesuser activity information.

Power conservation apparatus 66 alters video information in the inactiveportion(s) such that the display device will consume less power whenoutputting the video information. Power conservation control 68 has aninput that receives user activity information from monitoring apparatus64, an input from clock 62 that receives temporal information, an inputfrom edge detection apparatus 79 that receives perimeter information ifneeded, input from sensor 76 that receives an indication of powerconsumption, and an input from power control logic 70 that receivesstored logic according to power conservation techniques describedherein. Power conservation control 68 determines how video informationin the inactive portion is altered to reduce power.

Power conservation control 68 determines an alteration to videoinformation according to stored power conservation logic, and outputs asignal indicative of the alteration. To do so, control 68 coordinatesinput from monitoring apparatus 64, clock 62, power sensor 76, and powercontrol logic 70. For example, control 68 may implement a luminancereduction scheme for a set of pixels in an inactive portion once athreshold activity time has been reached for a graphics component in theinactive portion. This luminance reduction then uses output frommonitoring apparatus 64 to determine whether an inactive graphicscomponent is available and to determine the spatial dimensions outsidethe active component for the inactive graphics component if the twographics components overlap. Magnitude and timing of the luminancereduction are determined according to stored instructions acquired frompower control logic 70. Input from clock 62 is used to determine whenthe threshold activity or power reduction interval time has been reachedand when to apply the luminance reduction.

Power conservation control 68 is also configured to receive input frommonitoring apparatus 64 to determine when to reactivate inactiveportions. Thus, in response to user activity in the inactive portion,control 68 reactivates the video information in the inactive portion asit was existed before any alteration. To facilitate reactivation, videoinformation for inactive portions that have been altered may be storedas it existed without any alterations in video buffer 72.

Power control logic 70 stores data and instructions that allow aprocessor to implement the techniques described herein. For example,power control logic 70 may include nonvolatile memory that stores timingparameters for a threshold inactivity time and power reduction intervalestablished by a user. In one embodiment, the logic stores instructionsthat allow the user to set a threshold inactivity time and powerreduction interval amongst a range of possible values. In anotherembodiment, the logic stores instructions that are implemented by designwith no user input. Logic 70 may also store instructions that convertpixel values between color schemes to reduce one of a red, green, orblue value for a set of pixels in an inactive portion such that thedisplay device will consume less power.

Video buffer 72 couples to an input of video adaptor 74 and stores videoinformation. Video buffer 72 stores video information from one or moreinactive portions without any alterations that reduce power consumption.Video buffer 72 may also store altered video information betweenconsecutive alterations. More specifically, altered video informationthat exists before a first threshold inactivity time may be storedwithin video buffer 72, and stored before each subsequent alterationaccording to continuous power reduction intervals. Although video buffer72 is illustrated as a single unit, is understood that buffer systemsmay employ one or more discrete storage components. In particular,different a buffer may be used to store video information without anyalterations than a buffer used to store altered video information inbetween multiple power reduction intervals. One or more RAM memorycomponents are suitable for use as video buffer 72.

In one embodiment, power conservation control 68 does not change videoinformation and relies on outside source to do so. In this case, powerconservation apparatus 66 includes a video adaptor 74 that receives asignal produced by power conservation control 68 and alters videoinformation in the inactive portion based on the signal. Video adaptor74 creates a set of signals that display pixelated video information foran image. Video adaptor 74 may correspond to a graphics controller,graphics co-processor, graphics accelerator, or other video controllerthat is commercially available from a variety of vendors. Suchcontrollers are often available as cards that comprise a circuit boardwith memory and a dedicated processor. Video adaptor 74 may already beimplemented within a computer system, as is common in desktop or laptopcomputer systems. An output line of video adaptor 74 provides thealtered video data in the inactive portions. In one embodiment, videoadaptor 74 converts digital information to analog information. Inanother embodiment, on laptops that comprise an LCD screen for example,the data remains digital.

Output video buffer 78 is configured to receive the altered videoinformation from an output of video adaptor 74 and may receive unalteredvideo information from video buffer 72. Output video buffer 78 isconfigured or designed to output, to display device 58, a) activegraphics component video information for display in the active portionof a display area, and b) the altered video information for display inthe inactive portion. Display device 58 displays a) and b)simultaneously. Again, although output video buffer 78 is illustrated asa single unit, is understood that buffer systems may employ one or morediscrete storage components. One or more RAM memory components aresuitable for use as video buffer 72.

A clock 62 provides a temporal reference for user activity. Output linesfor clock 62 are coupled to inputs for monitoring apparatus 64 and/orpower conservation control 68; and provide a temporal signal tomonitoring apparatus 64 and/or power conservation control 68. Mostcomputer systems include a digital clock suitable for use as clock 62.Temporal information from clock 62 may be useful to allow powerconservation apparatus 66 to alter video information in an inactiveportion after a threshold inactivity time of inactivity in the inactiveportion. In addition, temporal information from clock 62 allows powerconservation apparatus to timely apply a second alteration to thealtered video information in the inactive portion after a first powerreduction interval.

In one embodiment, system 60 comprises a power sensor 76 that monitorspower consumption—both active and predicted. Power sensor 76 may: detectpower actively consumed by display device 58, estimate power consumptionbased on video output from video adaptor 74, track available powerresources provided by a battery, and estimate power conservation andsavings based on control signals and alterations to video outputprovided by control 68. Power sensor 76 is coupled to power conservationcontrol 68. In one embodiment, power sensor 76 provides an estimation ofpower savings and consumption for altered video information. In aspecific embodiment, power sensor 76 couples to video adaptor 74 andprovides an estimation of power savings and consumption for the alteredvideo information based on the altered video information output fromvideo adaptor 74. This may be accomplished by mathematical analysis ofpower required by display device for video output, versus the alteredvideo information. For an OLED device where current is proportional tovideo output for each individual pixel, this analysis may constitutedetermining the power required for altered video information based on acumulative assessment of power consumption for individual pixels in aninactive portion of the display area.

An estimation of power consumption may also be provided for an activeportion without any alterations. Power sensor 76 may then provide powerconsumption output for a display area that spatially varies according toan active portion and one or more inactive portions. Power sensor 76 mayalso provide an estimation of spatial power consumption that would berequired for an inactive portion before any alteration, which is usefulfor comparative purposes and quantifying conservation. An output line ofpower sensor 76 couples to an input of power conservation control 68 andallows control 68 to alter video output based on one or more of: poweractively consumed by display device 58, video output from video adaptor74, and available power provided by a battery, all of which can becombined with estimated power conservation for alterations to videoinformation determined by control 68.

In one embodiment, system 60 also employs an edge detection apparatus 79that facilitates spatial mapping of graphics components. Thus, edgedetection apparatus 79 may be called upon by monitoring apparatus 64 toproduce perimeter information for graphics components that do notreadily include characteristic perimeter information in their bitmap.Edge detection apparatus 79 then probes video information for a graphicscomponent (such as that included in a bitmap for the graphicscomponent), builds a perimeter or shape based on the video information,and outputs the perimeter information for the graphics component to oneof monitoring apparatus 64, power conservation control 68 or buffer 72for storage therein.

Graphics-based user interfaces employ what are referred to as graphics“controls”. A graphics control is a discrete video object, for displayby a display device, which can be manipulated by a user to alter one ormore graphics outputs or effects and/or to initiate an action in anassociated application program. The graphics control often includes itsown bitmap comprising an array of pixel values. FIG. 3 illustrates apower conservation graphics control 140 for applying power conservationtechniques in accordance with one embodiment of the present invention.

Power conservation graphics control 140 facilitates interface between auser and a program run on a computer that allows the user to alter powerconsumption for a display device which outputs video information for thecomputer. Specifically, graphics control 140 allows the user to altervideo information output by a display device to reduce powerconsumption.

Power conservation graphics control 140 comprises a number of powerconservation control tools 142-149 that allow a user to set one or moreparameters for a power conservation program, which alters videoinformation in an inactive portion of a display area that is outside anactive portion of the display area. The power conservation programalters video data in response to user inactivity in the inactive portionsuch that the display device will consume less power when simultaneouslydisplaying the video information in the active portion and the alteredvideo information in the inactive portion than an amount of power thatwould be required to display the video information in the active portionand the inactive portion without the alteration. The power conservationcontrol tools 142-149 have a text labels that, along with theirpictorial representations, describes their function.

Power conservation graphics control 140 allows the user to set one ormore power schemes 141. A power scheme refers to a predefined collectionof power options, and simplifies usage by allowing the user to setmultiple parameters with a single choice and action. Two power schemesare shown for graphics control 140: ‘plugged in’ scheme 141 a and‘battery use’ scheme 141 b. Other exemplary power schemes include laptopuse and PDA use. A user may apply a power scheme as is. Alternatively,power schemes 141 allow a user to tailor and apply customized settingsby using a pre-existing power scheme as a starting point forcustomization. Power scheme control 141 thus allows a user to customizevideo alteration response for different power states of the computer,operation states for the computer system, different display devices, anddifferent graphics components. Responses for graphics components willvary with the device and programs installed thereon, and may includeseparate responses for a word processing program, an Internet Browserinterface, a graphics control, a music player program, and a video game,for example.

A threshold time tool 145 allows a user to set a threshold inactivitytime after which the video information in the inactive portion isaltered for the first time. A window 145 a allows a user to input adesired threshold inactivity time, while a scroll button 145 b allows auser to select a threshold inactivity time from a stored set ofthreshold times. This may be done for each power scheme 141. The usermay input a desired threshold inactivity time by moving an on-screenpointer or manipulanda to window 145 a and typing a desired time. Thegraphics-based user interface interprets this input as an instructionfrom the user, and adapts power conservation control according to theinput. In one embodiment, a user may set a threshold inactivity timefrom about 10 seconds to about 2 hours. In another embodiment, the usermay set the threshold inactivity time from about 1 minute to about 10minutes. Threshold time tool 145 also includes an ‘off’ state that turnsthis option off. In this case, power conservation is applied immediatelyupon inactivity in an inactive portion according to the power reductioninterval time.

An interval time tool 146 allows a user to set a power reductioninterval at which the video information in the inactive portion iscontinuously altered after each power reduction interval. A window 146 aallows a user to input a desired power reduction interval, while ascroll button 146 b allows a user to select a power reduction intervalfrom a stored set. Again, this may be done for each power scheme 141.

A luminance reduction tool 147 allows a user to set a luminancereduction for video information in the inactive portion. In oneembodiment, tool 147 allows the user to set luminance reductions using arelative magnitude, such as a percentage of a maximum luminance orrelative sizes of a histogram that characterizes video information inthe inactive portion. As shown, ‘plugged in’ scheme 141 a shows a scalar2 percent luminance reduction of the maximum luminance for the displayarea, which will occur at each power reduction interval. Battery usescheme 141 b shows a 10 percent histogram compression, which will occurat the threshold inactivity time and at each power reduction interval.

A luminance minimum tool 148 allows the user to set a lower luminancelimit that sets a minimum luminance value for pixels in the inactiveportion. The lower luminance limit may be a minimum luminance based onthe original luminance for a pixel, as is currently set for ‘plugged in’scheme 141 a. Battery use scheme 141 b alternately shows a shut off thatis applied after 15 minutes, which turns all video information in theinactive portion to black at the specified time.

An apply button 149 allows a user to initiate changes made withingraphics control 140 onto the display device and graphics-based userinterface. Thus, after specific changes and power consumption parametersare selected and set, the user may click apply button 147 to initiatethe changes.

In addition to the specific tools described above, power conservationtools for graphics control 140 may include combinations of commonconventional graphics control tools such as buttons, options, scrollbars, pictures, spin dials, list boxes, text boxes, etc. For example, acheck box is a control tool that comprises an empty box. When a userselects the box, it is filled with an “X” or other suitable informationto indicate that the user has selected an option corresponding to thebox. One or more check boxes may be used to allow a user to quicklyselect from one or more predetermined luminance reduction schemes.Graphics control 140 also includes a ‘cancel’ button that closesgraphics control window 140 without initiating any changes, and an ‘OK’button that closes graphics control window 140 and applies any changesas described above.

FIG. 4A illustrates a process flow 200 for reducing power consumed by adisplay device in accordance with one embodiment of the invention. Whilethe present invention will now be described as a method and separableactions for reducing power consumption, those skilled in the art willrecognize that the subsequent description may also illustrate hardwareand/or software systems and components capable of performing the methodand actions.

Process flow 200 begins by displaying an active graphics component in afirst portion of a display area provided by the display device (202).The active graphics component implies user activity within itsboundaries, the nature of which will depend on the program orapplication associated with the graphics component. Common activegraphics component output video information for one of: a wordprocessing program, an Internet Browser interface, a graphics control, amusic player program, and a video game, for example. User activity forthe graphics control may include the manipulation of buttons, options,scroll bars, pictures, spin dials, list boxes, text boxes, and otheractivities described above with respect to FIG. 3.

Process flow 200 monitors user activity within the display area (204).This comprises spatially determining the location of user input andwhether the input extends outside the active graphics component. Inresponse to user inactivity in an inactive portion of the display areathat is outside the first portion, video information in the inactiveportion is then altered such that the display device will consume lesspower when displaying the altered video information than an amount ofpower that would be required to display the video information withoutthe alteration (206).

After the alteration, the active graphics component is simultaneouslydisplayed in the first portion while displaying the altered videoinformation in the inactive portion (208).

FIG. 4B illustrates a process flow 210 for reducing power consumed by adisplay device in accordance with another embodiment of the invention.Process flow 210 begins by setting a power conservation scheme (211). Apower scheme refers to a collection of power options that dictate howand when video information is altered to reduce display device powerconsumption. In one embodiment, a graphics control such as thatdescribed with respect to FIG. 3 may allow a user, for example, to set alower limit that sets a minimum RGB value for pixels in inactiveportion. In another embodiment, a power conservation system is stored ona computer and implements a power conservation scheme as described abovewithout user input.

After the power conservation scheme has been established, one or moregraphics components are initiated and displayed by the user and computersystem (212). Process flow 200 then monitors user activity within thedisplay area and graphics components (213). This comprises spatiallydetermining the location of user input and whether it is within thebounds of a graphics component. Based on the user input, process flow210 defines an active portion and one or more inactive portions based onthe user activity (214).

Process flow 210 then monitors activity in the inactive portion overtime to determine if user activity in the inactive portion continues(216). If user activity occurs in the inactive portion, process flow 210then returns to defining a new active portion and new inactive portionsbased on the user activity (214). If no user activity occurs, a check ismade as to whether a threshold inactivity time has been establishedaccording to the power conservation scheme (218). In one embodiment, thepresent invention employs a threshold inactivity time from about 10seconds to about 2 hours. In another embodiment, the present inventionemploys a threshold inactivity time from about 1 minute to about 10minutes.

If a threshold inactivity time has been set, and user inactivity in theinactive portion continues until the threshold inactivity time, thenprocess flow 210 alters video information in the inactive portionaccording to a change determined in the power scheme for the thresholdinactivity time (220). In a specific embodiment, this comprises alteringvideo information not required for shape detection of the graphicscomponent. Suitable shape detection reductions techniques, such asreducing for internal portions of a graphics component having a largewhite internal portion, were described respect to FIGS. 1A-1E. For colordisplay outputs, the alteration commonly reduces one of a red, green, orblue value for a set of pixels in the inactive portion such that thedisplay device will consume less power when displaying the altered videoinformation. After the video information is changed, the active graphicscomponent and altered video information are then simultaneouslydisplayed (208).

After the threshold inactivity time alteration (220) and display (208),process flow 210 continues to monitor user activity in the inactiveportion (217). If user inactivity in the inactive portion continues fora power reduction interval, a second alteration is applied to the videoinformation in the inactive portion such that the display device willconsume less power when displaying the secondly altered videoinformation than an amount of power that would be required to displaythe video information without the second alteration. The secondalteration occurs after the power reduction interval according to achange determined for the power reduction interval (222). For example,the second alteration may comprise a second alteration to the videoinformation not required for shape detection that results in greaterpower conservation than the first alteration. In one embodiment, a powerreduction interval from several milliseconds to about 30 minutes issuitable for some graphics based user interfaces. In another embodiment,a power reduction interval from about 1 minute to about 10 minutes issuitable. After the video information is changed, the active graphicscomponent and altered video information are then simultaneouslydisplayed (208).

If a threshold inactivity time has not been established (218),alteration occurs directly according to the power reduction intervalscheme. In a specific embodiment, video alteration occurs on a gradualand high frequency basis. In this case, video information within theinactive portion may begin, for example, within ten seconds, 5 secondsor 1 second of user inactivity. Subsequent minute alteration may occurat a high frequency such that noticeable changes to the videoinformation are not substantially detectable. Subsequent minutealterations may include small scalar luminance reductions applied ateach power reduction interval.

Steps 217, 222, and 208 may then continue to repeat based on userinactivity in the inactive portion and according to power scheme design,e.g., for a third alteration and power reduction. In one embodiment, thepresent invention increases alterations to video data in subsequentalterations such that reductions in power consumption begin graduallyand increase as time proceeds. The power scheme may also include a stopcondition that prevents further alteration of video data (225). In oneembodiment, process flow 210 applies a lower limit that limits pixelvalues in the inactive portion. For example, the lower limit may be apercentage of initial pixel value for a pixel, such as an initialluminance or chroma value. If the lower limit has been met for everypixel in the inactive portion, process flow 210 is finished. Until thiscondition is met, steps 217, 222, and 208 may repeat. In addition, ifuser activity occurs in the inactive portion (217) before the next powerreduction interval, process flow 210 restores the video information inthe inactive portion to its original state before any alterations wereapplied (224) and process flow 210 returns to defining a new activeportion and new inactive portions based on the user activity (214).

FIG. 4C illustrates a process flow 230 for reducing luminance in one ormore inactive portions in accordance with one embodiment of theinvention. Process flow 230 begins by setting a luminance reductionscheme (231). A graphics control such as that described with respect toFIG. 3 may allow a user, for example, to set a lower luminance limitthat sets a minimum luminance value for pixels in inactive portion.After the power conservation scheme has been established, one or moregraphics components are initiated and displayed (232). Process flow 200then monitors user activity within the display area and graphicscomponents (233) and defines an active portion and one or more inactiveportions based on user activity (234).

Process flow 230 monitors activity in the inactive portion to determineif user activity in the inactive portion continues (236). If no useractivity occurs, and if a threshold inactivity time has been set, anduser inactivity in the inactive portion continues until the thresholdinactivity time, then process flow 230 alters video information in theinactive portion according to a change determined in the luminancereduction scheme for the threshold inactivity time (240). In oneembodiment, altering the video information comprises a luminancereduction for set of pixels in the inactive portion. Suitable luminancereductions techniques, such as reducing luminance value for the set ofpixels by a constant value, were described respect to FIGS. 1A-1E. Afterthe luminance reduction, the active graphics component and altered videoinformation are then simultaneously displayed (208).

If user inactivity in the inactive portion continues for a powerreduction interval (237), a second luminance reduction is applied to thevideo information in the inactive portion (242). In one embodiment, thesecond alteration may comprise a second luminance reduction that isgreater than the first luminance reduction or uses one or more histogrammanipulation techniques. In another embodiment, alteration includes ahistogram compression of pixel values for a set of pixels in theinactive portion. This may be followed by a reduction of pixel valuesfor the set of pixels using a constant that gives a pixel with thelowest histogram value a zero value. After the video information ischanged, the active graphics component and altered video information arethen simultaneously displayed (208).

Steps 237, 242, and 208 may then continue to repeat based on userinactivity in the inactive portion and according to a predeterminedpower scheme. Some stop conditions suitable for use for with continuousluminance reduction schemes include when a histogram for the set ofpixels reaches a minimum width (either through scalar manipulation orhistogram compression) or when a maximum luminance value in the inactiveportion reaches a predetermined minimum luminance. If the lower limithas been met, process flow 230 finishes. Steps 237, 242, and 208 repeatuntil the lower limit has been met. In addition, if user activity occursin the inactive portion (237) before the next power reduction interval,process flow 230 restores the video information in the inactive portionto its original state before any alterations were applied (244) andprocess flow 230 returns to defining a new active portion and newinactive portions based on the user activity (234).

In one embodiment, process flow 210 or 230 also differentiates betweenmultiple inactive portions, such as individual inactive graphicscomponents. In this case, process flow 230 may apply different luminancereduction schemes to each graphics component. For example, videoinformation in a background may be altered more aggressively than videoinformation in a music player program graphics component. The presentinvention may also apply different threshold inactivity time (loop 218,220, and 208) and power reduction intervals (loop 217, 222, and 208) foreach graphics component. In addition, power schemes may be set up foreach graphics components type by a user such that the graphics-baseduser interface applies a customized power conservation. In this case,the user may set large alterations to background video information todecrease power consumption from the background. Different portions of asingle graphics component may also be altered at different rates, suchas a control bar, toggle, icon and clock included in a background.Alternatively, a border portion of a graphics component that outputsvideo information for a spreadsheet program may be altered less than aninternal portion that comprises text.

The present invention finds use with computer systems such as desktopand laptop computers, personal digital assistants (PDAs), portablecomputer systems, and the like. FIG. 5 illustrates an exemplarygeneral-purpose computer system 300, representing a personal computersuitable for implementing the present invention.

Computer system 300 comprises a processor, or CPU, 302, system memory304, input/output (I/O) circuitry 306, display device 308, input device310, and system bus 312. System bus 312 permits digital communicationbetween system memory 304 and processor 302, as well as permits digitalcommunication between other components within system 300 and processor302 and/or system memory 304.

System memory 304 includes read only memory (ROM) 314 and random accessmemory (RAM) 316. ROM 314 stores a basic input/output system 318 (BIOS),containing basic routines that help to transfer information betweenelements within computer system 300, such as during start-up. Computersystem 300 may also include a hard disk drive 320, a magnetic disk drive322, and an optical disk drive 324. Magnetic disk drive 322 reads fromand writes to a removable floppy disk 326. Optical disk drive 324 readsfrom and may write to a CD-ROM disk 328 or other optical media. Thedrives and their associated computer-readable media provide non-volatilestorage for system 300. A number of program modules may be stored in thedrives, system memory 304, and/or RAM 310, including an operating system330, one or more application programs 332, other program modules 334,and program data 336. Although the description of computer-readablemedia above refers to a hard disk, a removable magnetic disk and aCD-ROM disk, those skilled in the art will appreciate that other typesof media are readable by a computer system, such as magnetic cassettes,flash memory cards, USB memory sticks, digital video disks, and thelike. In addition, not all computer systems, such as PDAs and otherportable devices may include every component shown with respect tosystem 300.

Processor 302 is a commercially available microprocessor such as one ofthe Intel or Motorola family of chips, or another suitable commerciallyavailable processor. Processor 302 digitally communicates with systemmemory 304 via system bus 312, which may comprise a data bus, controlbus, and address bus for communication between processor 302 and memory304. CPU 302 is also coupled to the I/O circuitry 306 by system bus 312to permit data transfers with peripheral devices.

I/O circuitry 306 provides an interface between CPU 302 and suchperipheral devices as display device 308, input device 310, audio output334 and/or any other I/O device. For example, a mouse used as inputdevice 310 may digitally communicate with processor 302 through a serialport 306 that is coupled to system bus 312. Other interfaces, such as agame port, a universal serial bus (USB) or fire wire, may also providedigital communication between a peripheral device and processor 302. I/Ocircuitry 306 may also include latches, registers and direct memoryaccess (DMA) controllers employed for interface with peripheral andother devices. Audio output 334 may comprise one or more speakersemployed by a headphone or speaker system.

Display device 308 is for displaying video information—both unalteredand altered—including graphics components, backgrounds, graphicscontrols such as those described herein, graphics-based user interfacesas described herein, and other visual representations of data. Displaydevice 308 may comprise a cathode ray tube (CRT), liquid crystal display(LCD), organic light emitting diode (OLED), or plasma display, of thetypes commercially available from a variety of manufacturers. Displaydevice 308 may also comprise one or more optical modulation devices, orthe like, used in projecting an image. Projection display devices thatproject an image onto a receiving surface are becoming more popular,less expensive, more compact; and may employ one or more opticalmodulation technologies as well as a wide variety of individual designs.Common optical modulation devices include those employing liquid crystaldisplay (LCD) technology and digital mirror device (DMD) technology.When used as a display device for a computer, these projection devicesprovide the potential for a much larger image size and user interface.

Display device 308 may also digitally communicate with system bus 306via a separate video interface, such as a video adapter 346. Videoadapter 346 may be responsible for assisting processor 302 with videographics processing including alterations as described herein. Videoadapter 346 may be a separate graphics card or graphics processoravailable from a variety of vendors that are well known in the art.

Input device 310 allows a user to enter commands and information intothe computer system 300, and may comprise a keyboard, a mouse, aposition-sensing pad on a laptop computer, a stylus working incooperation with a position-sensing display on a PDA, or the like. Otherinput devices may include a remote control, microphone, joystick, gamepad, scanner, or the like. As a further alternative, input device 332may be any set of switches capable of communicating a user input tocomputer system 350. Therefore, as used herein, the term input devicewill refer to any mechanism or device for entering data and/or pointingto a particular location on an image of a computer display. Input asdescribed herein may also come through intermediary devices. Forexample, a remote control may communicate directly with processor 302,or through an intermediary processor included in another device such asa VCR, television, a hybrid entertainment device such as a set-top box,or projector. The user may then input information to computer system 300using an infrared remote control device that communicates first with theintermediary device, and then to processor 302.

In operation, input device 332 allows a user to position a pointer andcreate active portions according to their input. The user input may alsoinclude input analyzed by processor 302 that specifies one or more powerscheme options. In one embodiment, a graphics-based user interfaceimplemented by computer system 300 is programmed to respond to commandsfrom processor 302 to display graphics controls such as those describedabove. To display a power conservation graphics control, processor 302issues an appropriate command, followed by an identification of datathat is to be used to construct the graphics control. As describedabove, such data comprises a number of power conservation control toolsthat allow a user to change how video data is altered due to inactivity.The graphics control may store and call a bitmap of pixel valuesrelating to each power conservation control tool. System memory 304 alsostores a number power conservation commands and instructions forimplementing the techniques described herein. The present invention maybe practiced in the context of an application program that runs on anoperating system implemented by computer system 300 or in combinationwith other program modules on computer system 300.

The present invention may be implemented on a range of computer systems.In addition to personal computers such as desktop computers and laptopcomputers, a variety of other computer systems and computer devicesemploying a digital processor, memory and a display device may implementthe present invention. Handheld computers and other small portabledigital devices such as cell phones and digital cameras are increasinglyintegrating video display and computer functionality, including theability to access the resources of an external network such as theInternet and the ability to output video data to external displaydevices. One current trend is hybrid entertainment devices thatintegrate the functionality of computer systems, audio, and televisions.In addition, set-top boxes associated with cable television services arebecoming much more sophisticated user interfaces as interactive servicesbecome available to cable customers. Any of these devices may employ andbenefit from the power conservation methods and systems describedherein, particularly when the systems are run on battery power. Thescope of digital computer systems is expanding hurriedly and creatingmany systems and devices that may employ the present invention. Ingeneral, any digital device employing an output display device thatvaries output power with video content may benefit from the presentinvention. Moreover, those skilled in the art will appreciate that theinvention may be practiced with other computer system configurations,multiple display device systems, multiprocessor systems,microprocessor-based or programmable consumer electronics,minicomputers, mainframe computers, and the like. The present inventionmay also be practiced on any system running a graphics-based userinterface from a computer-readable memory such as internal electronicmemory, magnetic-based mass storage, and/or optical-based mass storage.The memory is programmed to implement the techniques described above.

The present invention is particularly useful to portable computingdevices run with battery power, such as laptop computers, MP3 playersand personal digital assistants. Power conservation according to presentinvention may also lead to secondary power savings benefits. For aportable computing system that employs an OLED display device forexample, a reduction in current for individual pixel elements to displayless bright video information also results in less heat generation. Thisallows the portable device to spend less battery and limited energy onheat dissipation, reserving more energy for display and other functions.In addition, although the present invention has been discussed withrespect to reduced power consumption, energy and power are intended tobe interchangeable.

Embodiments of the present invention further relate to computer readablemedia that include program instructions for performing variouscomputer-implemented techniques. The media and program instructions maybe those specially designed and constructed for the purposes of thepresent invention, or any kind well known and available to those havingskill in the computer software arts. Examples of computer-readable mediainclude, but are not limited to, magnetic media such as hard disks,floppy disks, and magnetic tape; semiconductor memory, optical mediasuch as CD-ROM disks; magneto-optical media such as optical disks; andhardware devices that are specially configured to store programinstructions, such as read-only memory devices (ROM), flash memorydevices, EEPROMs, EPROMs, etc. and random access memory (RAM). Examplesof program instructions include both machine code, such as produced by acompiler, and files containing higher level code that may be executed bythe computer using an interpreter.

Graphics controls and graphics-based user interfaces such as thosedescribed herein may be implemented using a number of computerlanguages. One suitable language is Java, available from SunMicrosystems of Sunnyvale, Calif. Another suitable language is theMicrosoft Windows.RTM. programming environment, detailed in theMicrosoft Windows 3.1 Guide to Programming, Redmond, Wash.: MicrosoftPress, 1987-1992, in which the graphics controls may be implementedusing operating system calls.

Although the foregoing invention has been described in some detail forpurposes of clarity of understanding, those skilled in the art willrecognize that various modifications may be made within the scope of theappended claims. For example, although the present invention hasdescribed luminance reduction of a background and graphics component atseparates rates, it is understood that luminance reduction may occur atthe same value for any video information outside an active portion. Inaddition, although the threshold time tool 145 of FIG. 3 allows a userto turn on/off a threshold inactivity time using a window and scrollbutton 145 b, the user may turn on/off the threshold time on/off with atoggle or button. The invention is, therefore, not limited to thespecific features and embodiments described herein and claimed in any ofits forms or modifications within the scope of the appended claims.

1. A method for reducing power consumed by a display device, the methodcomprising: displaying an active graphics component in a first portionof a display area provided by the display device; in response to userinactivity in an inactive portion of the display area that is outsidethe first portion, altering video information in the inactive portionsuch that the display device will consume less power when displaying thealtered video information than an amount of power that would be requiredto display the video information without the alteration; andsimultaneously displaying the active graphics component in the firstportion and the altered video information in the inactive portion. 2.The method of claim 1 wherein the alteration to the video information inthe inactive portion occurs after a threshold inactivity time.
 3. Themethod of claim 2 further comprising a second alteration to the alteredvideo information in the inactive portion that occurs after a firstpower reduction interval.
 4. (canceled)
 5. The method of claim 3 furthercomprising applying a lower limit that limits pixel values in theinactive portion.
 6. The method of claim 5 wherein the lower limit is apercentage of an initial pixel value for a pixel.
 7. The method of claim5 wherein the lower limit is one of a luminance limit or a chroma limitfor a pixel.
 8. The method of claim 1 wherein the active graphicscomponent outputs video information for one of: a word processingprogram, an Internet Browser interface, a graphics control, a musicplayer program, and a video game.
 9. The method of claim 8 wherein theactive graphics component outputs video data for the word processingprogram and user activity for the word processing program comprises oneof: typing in the first portion of the display area, positioning apointer within the portion of the display area and clicking a button,and manipulating a menu within the portion of the display area.
 10. Themethod of claim 1 wherein the inactive portion comprises graphicscomponent video information included in an inactive graphics componentand the user inactivity is based on a program associated with theinactive graphics component. 11-12. (canceled)
 13. The method of claim 1wherein altering the video information in the inactive portion comprisesa luminance reduction for a set of pixels in the inactive portion.14-19. (canceled)
 20. The method of claim 1 further comprisingmonitoring user activity within the display area.
 21. The method ofclaim 1 further comprising, in response to user activity in the inactiveportion, displaying the video information in the inactive portion as itwas displayed before the alteration. 22-23. (canceled)
 24. The method ofclaim 1 wherein the alteration reduces one of a red, green, or bluevalue for a set of pixels in the inactive portion such that the displaydevice will consume less power when displaying the altered videoinformation.
 25. A method for reducing power consumed by a displaydevice, the method comprising: displaying an active graphics componentin a first portion of a display area provided by the display device; inresponse to user inactivity in an inactive portion of the display areathat is outside the first portion, reducing luminance for a set ofpixels in the inactive portion such that the display device will consumeless power when displaying the reduced luminance video information thanan amount of power that would be required to display the videoinformation without the luminance reduction; and simultaneouslydisplaying the active graphics component in the first portion and thereduced luminance video information in the inactive portion.
 26. Themethod of claim 25 wherein the luminance reduction comprises reducingluminance values of all pixels in the inactive portion by a constantvalue.
 27. The method of claim 26 wherein the constant value includes afunction of one of a) a maximum luminance for the inactive portion, andb) a maximum luminance provided by the display device.
 28. The method ofclaim 25 further comprising a second luminance reduction for the set ofpixels in the inactive portion. 29-31. (canceled)
 32. The method ofclaim 25 wherein the luminance reduction occurs after a thresholdinactivity time.
 33. The method of claim 25 further comprising setting alower luminance limit that sets a minimum luminance value for pixels inthe inactive portion.
 34. (canceled) 35-38. (canceled)